Hi Ravichand,
Actually, I don't think you need to create a alert for this scenario.
Because in IC WebUI, by standard design, if you already have MAX 5 manual sessions already open,
then the 'New session' button will wb inactive(Gray out). If the button in your system didn't
gray out, you need to apply note: 2187577 - CRM-IC: New Session button active even when max sessions reached.
https://launchpad.support.sap.com/#/notes/2187577
Also, the maximum number of CRM IC tabs to be opened is hard coded (up to 6 only(only can open 5 manually, another one is for incoming communication session), if you want to change the max
number of open tabs, please check SAP Note 1628185 to adjust the coding.
https://launchpad.support.sap.com/#/notes/162818
Also, please read note: 1597836 - HTTP session handling in IC multi session scenarios.
If you set the parameter as following, then if the max number of sm04 http sessions is reached, then system will send an error message like "The maximum number of sessions has been reached" to the browser instead of a generic HTTP 500 internal server error. For further details you might also check SAP Note 1427190.
https://launchpad.support.sap.com/#/notes/1597836
icm/HTTP/esid_max_ctx (set the max allowed number of SM04 http sessons)
icm/HTTP/esid_displace_ctx to FALSE.
is/HTTP/show_detailed_errors to TRUE
Best Regards,
Bruce